How to know some really good classical music pieces out there?

sadly, i am totally lost nowadays when it comes to get updated in classical music genre :(

back when i was small, i still knew a lot of classical music, which i mainly knew from my classical piano private-courses’s teachers.
and then, i’ve got to know some really great, touching, & beautiful pieces, as well as the composers, such as Chopin (his Waltz pieces is just soo beautiful! and also his Nocturne, especially the quite-popular Eb major one!...veryy beautiful!) , Tchaikovsky (Nutcracker, Swanlake!) , Beethoven (very virtuoso, majestic!), and Debussy (Claire de Lune is just very ‘dreamyy’!) .

but ever since i quit my classical piano courses, i am just clueless as how to still find (& perhaps get updated) classical music pieces, especially the ‘hidden gems’ GOOD ones!

so i want to ask: how do you usually know, or find some really good classical music pieces out there?
is it usually from radio-station?
or from friend’s or other person’s recommendations?
or from internet? Youtube? (how?)

the ‘hidden gems’ that i especially hope i’ll NOT miss out are pieces like:
– Chopin’s “romantic” Waltz, and Nocturnes
– Debussy’s Claire de lune
– as well as ‘crazy’ but also ‘beautiful’ FAST masterpiece such as Chopin’s Nocturne (for practicing and the ‘gigantic’ effect)

if any of you can also give suggestions to other classical pieces and composers (please describe in very detail) , i’d be really thankful & happy! :)
thanks.